The present invention relates to a helical scan type of video tape recorder (abbreviated in the following to VTR) utilizing segment recording, whereby one field of a video signal is divided into a plurality of segments which are recorded on respective tracks of a magnetic tape, and in particular to an improved VTR for segment recording whereby a satisfactory display image is obtained from a playback signal produced during varied-speed playback operation, when the playback signal segments are intermingled in an incorrect sequence
The rotary 2-head helical scan method is widely utilized as the basic operating method of video tape recorders (hereinafter referred to as VTRs) for domestic use. With that method, the speed of rotation of a rotary head cylinder (e.g. expressed in revolutions per second) is made equal to the frame frequency of the video signal (expressed in Hz), and one field of the video signal is recorded on one video track of a magnetic tape during 180.degree. of rotation of the head cylinder.
To utilize such a VTR to record a wide-band video signal, e.g. a high-definition television signal, it is necessary to increase the relative velocity between the magnetic tape and the record/playback heads, to thereby increase the signal bandwidth of recording on the magnetic tape.
For example, if it is assumed that a wide-band video signal is to be recorded which has a bandwidth that is six times that of the NTSC standard video signal, it will be necessary to use a technique such as rotation of the head drum at a speed which is equivalent to six times the frame frequency of the video signal, or division of the video signal into two channels, with the head drum being rotated at a speed which is equivalent to three times the frame frequency. With such methods, each field of the video signal is recorded as six tracks on the magnetic tape.
A recording method of this type, whereby each field of the video signal is divided into a plurality of segments along the time axis, with the segments being respectively recorded on separate video tracks, is referred to as a segment recording method. With such segment recording, during varied-speed playback operation (e.g. operation at a playback speed which is a multiple of the standard playback speed), the heads will scan diagonally across the tracks of the magnetic tape. As a result, the positions of the segments in the playback displayed image will be displaced from the correct positions, and portions of the image (in segment units) will be intermingled. It is therefore difficult to comprehend the displayed image thus produced during varied-speed playback operation, if segment recording is used.